HI @anubhav.s ,
I found a previous community post that I think solves a similar case if you want to check it out (Gallery Option - Q&A - Amazon Quick Community). Otherwise, I think based on what you have so far with the calculated fields that you have created, here is my thought process for this:
Select a Table visual, put ‘Gallery_Row’ in Group by, and your ‘Gallery_Col1/2/3’ fields in Values. Then go to Format visual → Field styling, select each column field, and choose “Show URLs as images.”
Regarding your external HTML workaround, Custom Content Visuals do support parameter-driven content through navigation actions, so you can dynamically update what’s displayed based on user filter selections. This means your S3-hosted gallery doesn’t have to be disconnected from the rest of your dashboard. See the Custom Content Visual docs for setup details.
Let me know if you have any further questions, this has been a very interesting use case to work on!